Who's statistics are we talking about? The Barna Group study from 2008 suggested no real difference from faith to lack of faith.
Divorce Among Adults Who Have Been Married
All adults... 33%
Evangelical Christians... 26%
"Born again" Christians... 33%
"other" Christians... 33%
non-Christian faith... 38%
Atheist or agnostic... 30%
Protestant... 34%
Catholic... 28%
White... 32%
Black... 36%
Hispanic... 31%
Asian... 20%
Conservative... 28%
Moderate... 33%
Liberal... 37%
How I read this is roughly one third of all marriages end in divorce, 64% success rate... not exactly a passing grade overall. However, "Atheists and agnostics" are below the average as is "Evangelical Christians." Inflating the numbers seems to be "other Christians" and "non-Christian Faiths." Confirmed by the spread between Catholics and Protestants, and somewhat helped by the spread between Conservative and Liberal.
This does thou negate your theory that "People who actually take their religion seriously have substantially higher marriage rates." Who are you to question what other faiths are serious?
https://www.barna.org/barna-update/...-and-divorce-statistics-released#.VikT78WrSHs